DANVILLE — Police will step up their presence at a Danville middle school Thursday after a threatening graffiti message put officers and school officials on edge.

According to Charlotte Wood Middle School principal Christopher George, concern among school staff and administrators first arose May 1 when graffiti, sprayed in a unique shade of yellow, coated part of a sign facing El Capitan Drive, the same street the school sits on. On Tuesday, what is believed to be the same paint was used on part of a bridge near the campus, according to several student reports George received. But in that incident, a threatening message was written that caused extreme worry.

“The message painted said, ’12 people, May 8,'” George said.

Despite the fact the message was found off-campus, George said the distinctive paint led him and others to assume the two incidents were related. Though no students were threatened and though there is no indication the graffiti was done by a student, George said he and police are not taking any chances.

“The fact that it was off campus doesn’t matter to us,” George said. “We have to do what we need to do to keep students safe, not just (Thursday) but every day.”

George added that while Charlotte Wood Middle School does not have a school resource office present on campus every day, police presence will be increased at the school Thursday should any issues arise.

Otto Warmbier was arrested in January 2016 at the end of a brief tourist visit to North Korea. He had been medically evacuated and was being treated at the University of Cincinnati Medical Center when he died at age 22.